Computer-security firm FireEye has told the Federal Bureau of Investigation that a group of cyberthieves may be attempting to gain an edge on Wall Street by targeting chief financial officers, advisory firms and others involved in mergers, acquisitions and other market-moving events.

In one case, the group focused on employees privy to changes in closely watched government-reimbursement rates at a publicly traded health-sector firm. In another, hackers posed as an adviser to one of two companies in a potential acquisition.

Since the middle of last year, these hackers penetrated more than 100 companies that are either publicly traded or advising publicly traded firms, FireEye said. Most of the targets are health care or pharmaceutical companies, FireEye said; it declined to name specific firms.

FireEye said it alerted the FBI of its findings during the past week.

“There’s nothing else that this could have been going after other than to game the market,” said Jen Weedon, a manager at FireEye’s Mandiant unit, best known for researching foreign hackers.

FireEye researchers said they aren’t aware of any irregular trading linked to their findings.

Cyberattacks have long targeted information that could be handy for investors trying to gain a leg up. But former U.S. officials and experts at other security firms say they’ve not seen evidence suggesting hacked information was behind a suspicious trade.

Hackers appear to target specific employees — particularly those with access to potentially market-moving information — and seek specific sets of data, FireEye said. Moreover, it said the hackers appear to speak English.

These hackers appeared interested in information that would make a stock move up or down, FireEye said.

In one e-mail meant to trick an executive to hand over e-mail account information, the hackers warned that another employee “may have unwittingly divulged confidential company information regarding pending transactions” in a rant posted on an investment message board.

“This smells very different” than Chinese hacking investigated by Mandiant, Weedon said. She added the hackers could be “home grown” or based in Western Europe.

FireEye’s disclosure Monday comes as the financial services sector has dramatically upped its spending on cybersecurity, which could prove to a boon for companies like FireEye and large consulting firms like Deloitte. Financial services companies plan to boost cybersecurity budgets by a combined $2 billion during the next two years, according to a November report by the consulting firm PricewaterhouseCoopers, which also provides anti-hacking services.

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